You can't change a message after you've sent it, but you can resend it as iMessage

Once a text message leaves your phone, you cannot edit it or convert it to iMessage. What you can do is delete the message thread and start a new conversation using iMessage instead. If the person you messaged has an iPhone, iPad, or Mac, iMessage will turn on automatically the next time you text them — you'll see the message bubble turn blue instead of green, which signals iMessage is active.

The confusion usually comes from seeing a green bubble (regular SMS text) when you expected a blue bubble (iMessage). This happens when iMessage didn't activate for that contact, usually because their device wasn't reachable when you first messaged them, or because they don't have an Apple device.

Key Takeaways

  • iMessage activates automatically when you text someone with an Apple device, shown by a blue message bubble instead of green.
  • You cannot convert a message you've already sent — you can only delete the thread and start fresh.
  • If iMessage isn't turning on for a contact, check that they have an Apple device and that their phone is powered on.
  • Turning iMessage off and back on in Settings can fix cases where it's stuck on SMS for a specific contact.
  • iMessage only works over Wi-Fi or cellular data, not through your phone plan's text message allowance.

How to delete a message thread and start over with iMessage

Open the Messages app and find the conversation you want to restart. Press and hold on the thread name at the top of the screen, then tap Delete. Confirm the deletion.

Now open a new message to that same contact. If they have an Apple device, iMessage will activate and you'll see a blue compose box at the bottom of the screen. Type your message and send it. The blue bubble confirms iMessage is now active for this contact.

If the compose box stays green, iMessage is not available for that person. This means either their device is off, they don't have an Apple device, or iMessage is disabled in their Settings.

Why iMessage doesn't always turn on automatically

iMessage requires the other person to have an Apple device that is powered on and connected to the internet. If you text someone with an iPhone but their phone is off or in airplane mode, iMessage won't activate — your message will send as a regular text instead.

Sometimes iMessage gets stuck on SMS for a specific contact even though they have an iPhone. This usually happens if their device was unreachable when you first messaged them. To fix this, go to Settings > Messages and toggle iMessage off, wait 10 seconds, then toggle it back on. Send a new message to that contact — iMessage should activate this time.

If you recently switched from Android to iPhone, Apple's system may not recognize you as an iMessage user yet. Ask your contacts to delete your old phone number from their phone and add it back, or wait a few hours for the system to update.

The difference between iMessage and regular text messages

iMessage is Apple's messaging service that works over Wi-Fi or cellular data. Regular text messages (SMS) use your phone plan's text allowance and work on any phone. iMessage messages appear in blue bubbles, while SMS messages appear in green.

iMessage includes features that SMS doesn't: read receipts (you can see when someone has read your message), typing indicators (the three dots showing someone is typing), and the ability to send high-quality photos and videos. iMessage also works across all Apple devices — you can start a conversation on your iPhone and continue it on your iPad or Mac.

If you're on a limited text plan, iMessage saves your text allowance because it uses data instead. However, if you lose Wi-Fi or cellular connection, iMessage messages won't send until you're back online.

What to do if iMessage is turned off on your phone

Open Settings and scroll down to Messages. Tap it and look for the toggle next to iMessage. If it's gray (off), tap it to turn iMessage on. Your phone will connect to Apple's servers, which takes a few seconds.

If the toggle is already on but iMessage still isn't working, try turning it off, waiting 10 seconds, and turning it back on. This refreshes your connection to Apple's system.

If you see a message saying "Waiting for activation," your phone is trying to set up iMessage but hasn't finished yet. This usually completes within a few minutes, but if it takes longer than 15 minutes, restart your phone.

How to check if someone has an Apple device

The easiest way is to look at the message bubble color. If you send a message and it appears in a blue bubble, iMessage is active and the person has an Apple device. If it's green, they don't have iMessage available.

You can also ask them directly, or check if they're listed in your contacts with an iPhone, iPad, or Mac next to their name. In the Contacts app, open their card and look at the device icons shown under their name.

Frequently Asked Questions

Can I change a message from green to blue after I've sent it?

No. Once a message is sent as SMS (green), it stays that way. You would need to delete the conversation and send a new message. If iMessage is available for that contact, the new message will send as iMessage (blue).

Why is my message green when I'm texting another iPhone user?

Their iPhone may be off, in airplane mode, or not connected to Wi-Fi or cellular data. iMessage needs an active internet connection. You can also check if they have iMessage turned off in their Settings, or if their Apple ID isn't set up correctly.

Does iMessage cost money?

No. iMessage is free and uses your Wi-Fi or cellular data plan. You don't pay per message. Regular SMS texts may count against your phone plan's text allowance, depending on your carrier.

What happens if I send an iMessage to someone without an Apple device?

The message will automatically fall back to SMS and appear as a green bubble. The person will receive it as a regular text message on their Android phone or other device.

Can I use iMessage on Android?

No. iMessage only works on iPhones, iPads, and Macs. Android users receive iMessages as regular text messages, but they cannot send iMessages themselves.